Red wood ants (Formica rufa) pheromone transmission. (Photo by Yuriy Bartenev on Shutterstock) In A Nutshell * Red wood ants carry Fructilactobacillus sanfranciscensis, the sourdough bacterium that can seed milk and trigger yogurt-like fermentation. * In lab conditions, four live ants added to warm milk led to curdling by morning at about pH 5 (store yogurt is ~4.2), with mild tang and grassy notes. * Ants contribute formic acid (about 1–2.5 g/L measured in the yogurt), lowering pH; ant-borne bacteria then make lactic and acetic acids and enzymes that cut milk proteins. * Only live ants yielded stable, desirable communities;...